JPH082884B2 - 1,3-Oxazin-4-one derivative, its production method and plant growth inhibitor - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel 1,3-oxazin-4-one derivative, a method for producing the same, and a plant growth inhibitor.

(B) Conventional Technology and Problems to be Solved by the Invention Conventionally, compounds belonging to 2,3-dihydro-4H-1,3-oxazin-4-one can be found in the following documents.

Chem.Pharm.Bull., 35 (5), 1860 (1987), Chem.Pharm.Bull., 35 (5), 1871 (1987), Heterocycles, 17 , 298 (1982), Tetrahedron Lett., 33 , 2905. (1976).

2,3-dihydro-4-H described in these documents
The 1,3-oxazin-4-one derivative has a substituent at the 2-position, which is different from the compound of the present invention in which the 2-position is a hydrogen atom.

Chem.Pharm.Bull., 31 (6), 1902 (1983) and
Kim. Geterotsikl. Soedin., 1987 (6), 740 describes a compound in which the 2-position is a hydrogen atom, but a compound in which the 3-position is an unsubstituted phenyl group or a 3-position methyl group is a carboxy group or A compound having a cyano group, which is essentially different from the compound of the present invention.

Further, no finding has been disclosed that suggests a plant growth inhibitory action of the 1,3-oxazin-4-one derivative represented by the formula (I).

(C) Means for Solving the Problems The present inventors have completed the present invention as a result of earnest research to obtain a novel 1,3-oxazin-4-one derivative as described above.

That is, the present invention has the general formula (I) (In the formula, R ¹ is selected from the group consisting of an alkyl group, a lower alkenyl group, a lower alkynyl group, a cycloalkyl group, a halogen atom, a lower alkyl group, a lower alkoxy group, a cyano group, a nitro group and a halogenated lower alkyl group. Optionally substituted with at least one group, optionally substituted with at least one group selected from the group consisting of an aryl group, a halogen atom, a lower alkyl group, a lower alkoxy group, a hydroxy group and a halogenated lower alkyl group. An aralkyl group or a halogenated lower alkyl group, R ² is a hydrogen atom, a halogen atom, an alkyl group, a lower alkenyl group, a lower alkynyl group, a cycloalkyl group halogen atom, a lower alkyl group, a lower alkoxy group, a cyano group, a nitro group and At least one group selected from the group consisting of halogenated lower alkyl groups An aralkyl group or a halogenated group which may be substituted with at least one group selected from the group consisting of an aryl group which may be substituted with, a halogen atom, a lower alkyl group, a lower alkoxy group, a hydroxy group and a halogenated lower alkyl group. A lower alkyl group, and R ³ is a hydrogen atom, a lower alkyl group, a lower alkenyl group,
A lower alkynyl group, a halogenated lower alkyl group or
R ² and R ³ together represent-(CH ₂ ) n- (n is 3 or 4). The present invention provides a 1,3-oxazin-4-one derivative represented by

According to the invention, the compound represented by the general formula (II) R ¹ —N═CH ₂ (II) (wherein R ¹ is the same as the definition in the general formula (I)) and the general formula (III) ) (In the formula, R ² and R ³ are the same as defined in the general formula (I).) 1,3
A method for producing an -oxazin-4-one derivative is provided.

Further according to the invention, the general formula (IV) (Wherein R ¹ is the same as defined in the general formula (I), R ³ is a hydrogen atom, a lower alkyl group, a lower alkenyl group, a lower alkynyl group or a halogenated lower alkyl group.) By reacting bromine in the presence of an inorganic base in an active solvent, the compound of the general formula (V) (Wherein R ¹ and R ³ have the same meanings as described above), and a method for producing a 5-bromo-1,3-oxazin-4-one derivative is provided.

In the general formula (I), the alkyl group is preferably
C ₁ a linear or branched alkyl group of _1-12, specifically methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec- butyl, tert- butyl, pentyl, isopentyl, hexyl, octyl, decyl , Dodecyl group and the like.

The term "lower" used in the present invention for a lower alkenyl group, a lower alkynyl group and the like means a group containing a _C2-6 carbon atom.

Lower alkenyl groups include vinyl, allyl, 1-propenyl, isopropenyl, 2-butenyl, 1,3-butadienyl, 2-pentenyl, 3-pentenyl, 1,4-pentadienyl, 1,6-heptadienyl, 1-hexenyl, 2-
A hexenyl group and the like are included. The lower alkynyl group includes
Examples include ethynyl, 1-propynyl, 2-propynyl, 1-butynyl, 3-butynyl, 1-pentynyl, 2-pentynyl, 4-pentynyl, 1-hexynyl, 5-hexynyl groups and the like.

The term "lower" used in a lower alkyl group, a halogenated lower alkyl group and the like means a group containing a C _1-6 carbon atom, specifically, methyl, ethyl, propyl,
Isopropyl, butyl, isobutyl, sec-butyl, pentyl, isopentyl, hexyl groups, etc., as well as fluoromethyl, difluoromethyl, trifluoromethyl, chloromethyl, dichloromethyl, trichloromethyl, bromomethyl, dibromomethyl, tribromomethyl, iodomethyl, 2 -Fluoroethyl, 2-chloroethyl, 2-
Bromoethyl, 2,2-difluoroethyl, 1-chloro-
2-fluoroethyl, 2,2,2-trifluoroethyl, 2,
2,2-trichloroethyl, 3-fluoropropyl, 3-
Examples include chloropropyl, 3,3,3-trichloropropyl, 4-chlorobutyl, 5-chloropentyl and 6-chlorohexyl groups.

As the aralkyl group, benzyl, phenethyl, 1-
Examples thereof include phenylpropyl, 3-phenylpropyl and 4-phenylbutyl groups, with benzyl and phenethyl groups being particularly preferred.

The aralkyl group which may have a substituent is selected from the group consisting of a halogen atom, a lower alkyl group, a lower alkoxy group, a cyano group, a nitro group, a hydroxy group and a halogenated lower alkyl group in an aromatic ring or an alkyl group. And substituted with at least one group. Specifically, 1- (2-chlorophenyl) ethyl, 3-chlorophenylmethyl, 1- (4-chlorophenyl) ethyl, 3-trifluoromethylphenylmethyl, 3-methoxyphenylmethyl, 1- (3-chloro-1- Methylphenyl) ethyl, 1- (4-chloro-1-methylphenyl) ethyl, 1- (2-chloro-1-methylphenyl) ethyl,
1- (3-trifluoromethyl-1-methylphenyl)
Ethyl, 1- (3-methoxy-1-methylphenyl) ethyl, 1-methyl-2-phenylethyl, 2-methyl-
2-phenylpropyl, 1,1-dimethyl-2-phenylethyl, 1-methyl-2-phenylpropyl, 2- (2
-Chlorophenyl) ethyl, 2- (3-chlorophenyl) ethyl, 2- (4-chlorophenyl) ethyl, 2-
(3-trifluoromethylphenyl) ethyl, 2- (3
-Methoxyphenyl) ethyl, 1-methyl-1-phenylethyl, 1-phenylethyl and the like.

Aryl groups include phenyl and naphthyl groups,
The aryl group having a substituent is a phenyl group or naphthyl group substituted with at least one group selected from the group consisting of a halogen atom, a lower alkyl group, a lower alkoxy group, a cyano group, a nitro group and a halogenated lower alkyl group. Groups are included.

The lower alkoxy group includes methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy,
Includes pentyloxy, hexyloxy groups and the like.

Cycloalkyl groups include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl groups and the like.

The halogen atom means a fluorine, chlorine, bromine or iodine atom.

Specific examples of the 1,3-oxazin-4-one derivative represented by the formula (I) include compounds shown in Table I-1 to Table I-9.

The 1,3-oxazin-4-one derivative of the present invention can be produced by the following method.

That is, a compound represented by the general formula (II) R ¹ —N═CH ₂ (II) (wherein R ¹ has the same meaning as described in the above formula (I)) and the general formula (III) (In the formula, R ² and R ³ have the same meanings as described in the above formula (I).) The compound represented by the general formula (I) is obtained by heating and reacting the compound in a solvent-free or inert solvent. (In the formula, R ¹ , R ² and R ³ have the same meanings as those described in the formula (I).), And a 1,3-oxazin-4-one derivative represented by the formula can be obtained.

In the production method of the present invention, the compound of the general formula (II) used as a raw material is an amine of the general formula (VI) R ¹ —NH ₂ (VI) (wherein R ¹ has the same meaning as described above). It is easily obtained by reacting with formalin. The compound of general formula (III) can be produced by a known method.

The reaction of the general formulas (II) and (III) can be carried out without solvent or in an inert solvent. Preferred inert solvents include benzene, toluene, xylene, methylene, tetralin, decalin and the like.

As the reaction temperature, a temperature of about 80 to 300 ° C. is usually used, but about 120 to 170 ° C. is preferable.

The amount of the compound represented by the general formula (III) used should be equivalent to or more than that of the compound represented by the general formula (II), but use of two or more equivalents has no significant effect.

The compound of formula (I) produced by the above reaction can be separated and purified by, for example, extraction, recrystallization and column chromatography.

Further, the compound of the general formula (I) in which R ² is a bromine atom is
General formula (IV) in which R ² is a hydrogen atom (In the formula, R ¹ has the same meaning as described in (I), R ³ represents a hydrogen atom,
A lower alkyl group, a lower alkenyl group, a lower alkynyl group, and a halogenated lower alkyl group are shown. ) Is reacted with bromine in the presence of an inorganic base in an inert solvent to give a compound of the general formula (V) A 5-bromo-1,3-oxazin-4-one derivative represented by the formula (wherein R ¹ and R ³ have the same meaning as in the above formula (IV)) can be obtained.

The inert solvent used in the reaction, methylene chloride, chloroform, halogen-containing solvent such as 1,2-dichloroethane,
Examples thereof include ether solvents such as tetrahydrofuran and diethyl ether, carbon disulfide, aromatic hydrocarbon solvents such as benzene and toluene, and methylene chloride and chloroform are particularly preferable.

As the inorganic base, salts of weak acids and alkali metals and alkaline earth metals are used, such as sodium carbonate,
Examples include potassium carbonate, lithium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, disodium phosphate, trisodium phosphate, sodium borate, potassium borate, lithium borate, sodium silicate, lithium silicate, and potassium silicate. . The amount of the inorganic base used is represented by the general formula (IV)
It is necessary to use an equivalent amount or more with respect to the compound shown in 1), but even if it is used in an amount of 20 equivalents or more, there is no significant effect, and it is effective to use 5 to 15 equivalents.

The reaction can be carried out at 0 ° C. to the boiling point of the solvent used, but it is preferable that the reaction is performed at 0 ° C. to 80 ° C.

Bromine is preferably used in the same amount or in a small excess amount with respect to the compound of the general formula (IV).

Further, the present invention is characterized by the following formula (I):
Provided is a plant growth inhibitor containing at least one 3-oxazin-4-one derivative as an active ingredient. The term “plant growth suppression” is used to mean death. For the plant growth inhibitor of the present invention, the active ingredient compound represented by the general formula (I) may be used as it is, but generally, a solid carrier, a liquid carrier, a surfactant, and the like, depending on the purpose of use. It is mixed with the formulation auxiliary agent to prepare wettable powders, granules, emulsions and the like.

In these preparations, the content of the 1,3-oxazin-4-one derivative is not particularly limited, but the wettable powder, 10 to 80% by weight as the active ingredient, 0.1 to 20% by weight in the granule, and 10 to 10% in the emulsion.
It is desirable to contain ˜50% by weight.

Examples of the solid carrier used in the formulation include kaolin, bentonite, clays, talc, diatomaceous earth, sieglite, zeolite, pyrophyllite, synthetic hydrous silicon oxide, fine powder or granules of calcium carbonate, and the like. Examples of the liquid carrier include aromatic hydrocarbons such as xylene and methylnaphthalene, alcohols such as ethanol, isopropanol, ethylene glycol and methyl cellosolve, ketones such as acetone, isophorone and cyclophohexanone, soybean oil and cottonseed oil. Vegetable oil, dimethylformamide, dimethylsulfoxide, acetonitrile,
Examples include water. Examples of the surfactant used for emulsification, dispersion, wet extension, etc. include polyoxyethylene alkyl ether, polyoxyethylene alkylaryl ether, polyoxyethylene fatty acid ester, polyoxyethylene sorbitan aliphatic ester, polyoxyethylene. Examples thereof include nonionic surfactants such as polyoxypropylene block polymers; anionic surfactants such as alkyl sulfate ester salts, alkyl sulfonates, alkylaryl sulfonates, polyoxyethylene alkyl sulfate ester salts and the like. Examples of the auxiliaries for formulation include lignin sulfonate, alginate, polyacrylates, polyvinyl alcohol, plant gums, carboxymethyl cellulose (CMC), hydroxyethyl cellulose (HEC) and the like.

In addition, for formulation, a conventionally used method such as mixing and dispersing can be adopted.

The wettable powder and emulsion prepared as described above are usually
It can be applied by diluting it with water and spraying the granules as it is with soil or foliage.

The plant growth inhibitor of the present invention is a nematicide, a fungicide,
It can also be mixed and used as a fertilizer or a soil conditioner.

When the soil treatment and the foliage treatment with the plant growth inhibitor of the present invention, the application rate can be varied in a considerably wide range,
Usually, the amount of the active ingredient per are is 0.1 to 200 g, preferably 1 to 100 g, and the application concentration is usually 1 to 80% by weight in the case of wettable powder, emulsion and water diluent. The application amount and application concentration are not limited to the above range, and can be increased or decreased depending on the type of formulation, application place, method, time, crop, degree of weed damage, weather conditions and the like.

EXAMPLES The present invention will be described more specifically by the following examples.

Example 1 3- (1-Methyl-1-phenylethyl) -2,3-dihydro-6-methyl-5-phenyl-4H-1,3-oxazin-4-one N-methylidene-1-methyl-1 -Phenylethylamine 0.78 g (5.4 mmol) and 2,2,6-trimethyl-5-phenyl-4H-1,3-dioxin-4-one 1.10 g (5.4 mmo
The mixture of l) was heated at 165 ° C for 30 minutes. After cooling, the reaction mixture was subjected to column chromatography (silica gel: W-20
Purification was performed using 0 and a solvent: hexane / ethyl acetate = 10/1) to obtain 1.13 g (yield 72.0%) of the title compound.

Melting point (° C): 97.0-99.0 ° C IR (cm ^-1 ): 3020,1660,1395,1355,1290,760 ¹ H-NMR (CDCl ₃ ) δ: 7.1-7.4 (m, 10H) 5.00 (s, 2H ),
1.85 (s, 3H), 1.80 (s, 6H) Examples 2 to 23 The following compounds were obtained in the same manner as in Example 1 except that compounds having different substituents were used as raw materials.

Example 2 3- (1-Methyl-1-phenylethyl) -2,3-dihydro-6-methyl-4H-1,3-oxazin-4-one IR (cm ⁻¹ ): 2970,1660,1395, 1250,880,700 ¹ H-NMR (CDCl ₃ ) δ: 7.0-7.4 (m, 5H), 5.13 (s, 1
H), 4.90 (s, 2H), 1.92 (s, 3H), 1.77 (s, 6H) Example 3 5-Bromo-3- (1-methyl-1-phenylethyl) -2,3-dihydro-6 -Methyl-4H-1,3-oxazin-4-one Melting point (° C): 126.0 to 127.0 ° C IR (cm ^-1 ): 2960, 1660, 1380, 1355, 1220, 700 ¹ H-NMR (CDCl ₃ ) δ : 7.1-7.4 (m, 5H), 4.90 (s, 2
H), 2.14 (s, 3H), 1.80 (s, 6H) Example 4 5-Bromo-3- (2,6-diethylphenyl) -2,3-
Dihydro-6-methyl-4H-1,3-oxazin-4-one Melting point (° C): 56.0 to 60.0 ° C IR (cm ^-1 ): 2980, 1685, 1460, 1390, 1160, 760 ¹ H-NMR (CDCl ₃ ) δ: 7.0-7.3 (m, 3H), 5.20 (s, 2
H), 2.57 (q, 4H), 2.28 (s, 3H), 1.20 (t, 6H) Example 5 3- (1-Methyl-1-phenylethyl) -2,3-dihydro-5-isobutyl-6 -Methyl-4H-1,3-oxazin-4-one IR (cm ^-1 ): 2960,1660,1400,1360,770,700 ¹ H-NMR (CDCl ₃ ) δ: 7.1-7.4 (m, 5H), 4.90 (S, 2
H), 1.9-2.2 (m, 2H), 1.93 (s, 3H), 1.75 (s, 6
H), 1.2-1.6 (m, 1H), 0.87 (d, 6H) Example 6 3- (2,6-diethylphenyl) -2,3-dihydro-5
-Isobutyl-6-methyl-4H-1,3-oxazine-4
-ON IR (cm ^-1 ): 2960,2870,1670,1460,1400 ¹ H-NMR (CDCl ₃ ) δ: 7.0-7.2 (m, 5H), 5.08 (s, 2
H), 2.47 (q, 4H), 2.2-2.4 (m, 2H), 2.03 (s, 3
H), 1.5-2.1 (m, 1H), 1.17 (t, 6H), 0.93 (d, 6H) Example 7 3- (1-Methyl-1-phenylethyl) -2,3-dihydro-5,6 -Dimethyl-4H-1,3-oxazin-4-one IR (cm ^-1 ): 3000,1660,1400,1360,1220,760 ¹ H-NMR (CDCl ₃ ) δ: 7.1-7.2 (m, 5H) , 4.83 (s, 2
H), 1.90 (s, 3H), 1.73 (s, 9H) Example 8 3- (1-Methyl-1-phenylethyl) -2,3-dihydro-6-phenyl-4H-1,3-oxazine- 4-on IR (cm ^-1 ): 3020,1660,1380,1220,760 ¹ H-NMR (CDCl ₃ ) δ: 7.0-7.7 (m, 10H), 5.77 (s, 1
H), 5.10 (s, 2H), 1.82 (s, 6H) Example 9 3- (1-Methyl-1-phenylethyl) -2,3-dihydro-6-propyl-4H-1,3-oxazine- 4-one IR (cm ^-1 ): 2960,1675,1385,700 ¹ H-NMR (CDCl ₃ ) δ: 7.1-7.4 (m, 5H), 5.15 (s, 1
H), 4.93 (s, 2H), 2.20 (t, 2H), 1.77 (s, 6H), 1.1
-1.8 (m, 2H), 0.93 (t, 3H) Example 10 5-Butyl-3- (1-methyl-1-phenylethyl) -2,3-dihydro-6-methyl-4H-1,3- Oxazin-4-one IR (cm ^-1 ): 3010,2950,1660,1400,1220,760 ¹ H-NMR (CDCl ₃ ) δ: 7.1-7.4 (m, 5H), 4.85 (s, 2
H), 2.0-2.3 (m, 2H), 1.93 (s, 3H), 1.75 (s, 6
H), 1.1-1.6 (m, 4H), 0.8-1.1 (m, 3H) Example 11 5-Benzyl-3- (1-methyl-1-phenylethyl) -2,3-dihydro-6-methyl- 4H-1,3-oxazin-4-one IR (cm ^-1 ): 2960, 1655, 1395, 700 ¹ H-NMR (CDCl ₃ ) δ: 7.1-7.4 (m, 5H), 7.10 (s, 5
H), 4.9 (s, 2H), 3.57 (s, 2H), 1.93 (s, 3H), 1.75
(S, 6H) Example 12 5-Bromo-3- (1-methyl-1-phenylethyl) -2,3-dihydro-6phenyl-4H-1,3-oxazin-4-one IR (cm ^-1 ): 3000,1665,1360,1215,760 ¹ H-NMR (CDCl ₃ ) δ: 7.0-7.5 (m, 10H), 5.07 (s, 2
H), 1.80 (s, 6H) Example 13 5-Bromo-3- (1-methyl-1-phenylethyl) -2,3-dihydro-6-propyl-4H-1,3-oxazin-4-one IR (cm ^-1 ): 2960,1675,1370,760 ¹ H-NMR (CDCl ₃ ) δ: 7.3-7.6 (m, 5H), 5.03 (s, 2
H), 2.55 (t, 2H), 1.84 (s, 6H), 1.1-1.8 (m, 2
H), 0.98 (t, 3H) Example 14 3- (1-Methyl-1-phenylethyl) -2,3,6,7
-Tetrahydrocyclopenta [e] -1,3-oxazin-4 (5H) -one IR (cm ^-1 ): 2930,1665,1410 ¹ H-NMR (CDCl ₃ ) δ: 7.1-7.4 (m, 5H) , 5.00 (s, 2
H), 2.4-2.7 (m, 4H), 1.6-2.2 (m, 2H), 1.78 (s, 6
H) Example 15 3-tert-butyl-2,3-dihydro-5-isobutyl-6-methyl-4H-1,3-oxazin-4-one IR (cm ^-1 ): 3020,2950,1650,1400 , 1220,760 ¹ H-NMR (CDCl ₃ ) δ: 4.95 (s, 2H), 2.1-2.3 (m, 2
H), 1.5-1.7 (m, 1H), 1.90 (s, 3H), 1.10 (s, 9
H), 0.87 (d, 6H) Example 16 2,3-Dihydro-5-isobutyl-6-methyl-3-
(1-Phenylethyl) -4H-1,3-oxazine-4-
ON IR (cm ^-1 ): 2950,1650,1400,760 ¹ H-NMR (CDCl ₃ ) δ: 7.22 (s, 5H), 5.75 (q, 1H), 4.5
−4.9 (m, 2H), 2.1−2.2 (m, 2H), 1.90 (s, 3H), 1.5
4 (d, 3H), 1.5-1.7 (m, 1H), 0.90 (d, 6H) Example 17 2,3-Dihydro-5-isobutyl-6-methyl-3-
Phenethyl-4H-1,3-oxazin-4-one IR (cm ^-1 ): 2950,1660,1400,700 ¹ H-NMR (CDCl ₃ ) δ: 7.11 (s, 5H), 4.58 (s, 2H) , 3.5
6 (dd, 2H), 2.85 (dd, 2H), 2.0-2.2 (m, 2H), 1.87
(S, 3H), 1.5-1.8 (m, 1H), 0.85 (d, 6H) Example 18 3-benzyl-2,3-dihydro-5-isobutyl-6
-Methyl-4H-1,3-oxazin-4-one IR (cm ^-1 ): 2950,1660,1400,700 ¹ H-NMR (CDCl ₃ ) δ: 7.17 (s, 5H), 4.80 (s, 2H ), 4.5
3 (s, 2H), 2.1-2.2 (m, 2H), 1.5-1.7 (m, 1H), 1.9
0 (s, 3H), 0.88 (d, 6H) Example 19 3-Cyclohexyl-2,3-dihydro-5-isobutyl-6-methyl-4H-1,3-oxazin-4-one IR (cm ^-1 ): 2930,2850,1650,1400,760 ¹ H-NMR (CDCl ₃ ) δ: 4.85 (s, 2H), 2.0-2.2 (m, 2
H), 1.90 (s, 3H), 1.1-2.0 (m, 12H), 0.88 (d, 6H) Example 20 3- (3-trifluoromethylphenyl) -2,3-dihydro-6-methyl-4H -1,3-Oxazin-4-one IR (cm ^-1 ): 3000,1675,1395,1340,1160,750 ¹ H-NMR (CDCl ₃ ) δ: 7.37 (s, 4H), 5.37 (s, 3H ), 2.0
3 (s, 3H) Example 21 5-Bromo-3- (3-trifluoromethylphenyl) -2,3-dihydro-6-methyl-4H-1,3-oxazin-4-one Melting point (° C): 117.0-118.0 ° C IR (cm ^-1 ): 3080,1675,1620,1340,1200,1110,805,700 ¹ H-NMR (CDCl ₃ ) δ: 7.40 (s, 4H), 5.40 (s, 2H), 2.2
7 (s, 3H) Example 22 3- (1-Methyl-1-phenylethyl) -2,3-dihydro-6-methyl-5- (1-methylpropyl) -4H
-1,3-Oxazin-4-one IR (cm ^-1 ): 2950,1660,1395,1350,700 ¹ H-NMR (CDCl ₃ ) δ: 7.1-7.3 (m, 5H), 4.83 (s, 2)
H), 2.43 (q, 1H), 1.93 (s, 3H), 1.73 (s, 6H), 1.5
-1.8 (m, 2H), 1.17 (d, 3H), 0.82 (t, 3H) Example 23 3- (3-trifluoromethylphenyl) -2,3-dihydro-6-methyl-5-phenyl-4H -1,3-Oxazin-4-one Melting point (° C): 86.0-91.0 ° C IR (cm ^-1 ): 3050,1660,1620,1400,1325,1175,1120,700 ¹ H-NMR (CDCl ₃ ) δ : 7.2-7.6 (m, 4H), 7.27 (s, 5
H), 5.48 (s, 2H), 1.94 (s, 3H) Example 24 5-Bromo-3- (1-methyl-1-phenylethyl) -2,3-dihydro-6-methyl-4H-1, 3-Oxazin-4-one 3- (1-methyl-1-phenylethyl) -2,3-dihydro-6-methyl-4H-1,3-oxazin-4-one (1.6g, 7mmol) and sodium carbonate A solution of bromine (0.36 ml, 7 mmol) in methylene chloride was slowly added dropwise to a mixture of (4.5 g, 42 mmol) in methylene chloride (10 ml) at room temperature. After stirring for 3 hours, the reaction mixture was filtered and the methylene chloride was evaporated under reduced pressure. The obtained residue is subjected to column chromatography (silica gel: W-200, solvent, hexane / ethyl acetate = 5/1).
0.8 g of the title compound (yield 37%)
Obtained.

The melting point, IR and ¹ H-NMR are shown in Example 3.

The following compound could be obtained in the same manner as in Example 24.

Example 25 5-Bromo-3- (2,6-diethylphenyl) -2,3-
Dihydro-6-methyl-4H-1,3-oxazin-4-one Melting point, IR, ¹ H-NMR are shown in Example 4.

Example 26 5-Bromo-3- (1-methyl-1-phenylethyl) -2,3-dihydro-6-phenyl-4H-1,3-oxazin-4-one IR, 'H-NMR results This is shown in Example 12.

Example 27 5-Bromo-3- (1-methyl-1-phenylethyl) -2,3-dihydro-6-propyl-4H-1,3-oxazin-4-one IR, ¹ H-NMR result This is shown in Example 13.

Example 28 5-Bromo-3- (3-trifluoromethylphenyl) -2,3-dihydro-6-methyl-4H-1,3-oxazin-4-one Melting point, IR, ¹ H-NMR result This is shown in Example 21.

Test Example Using the compounds obtained in Examples 1 to 7, 9 to 12, 14 to 20, 22, and 23, the growth inhibitory effect on plants was examined. That is, talc (50 parts by weight), bentonite (25 parts by weight), Solpol-9047 (manufactured by Toho Chemical Co., Ltd., 2 parts by weight), Solpol-5039 (manufactured by Toho Chemical Co., Ltd., 3 parts by weight) are mixed. A carrier was prepared. 50 parts by weight of a test compound and 200 parts by weight of the carrier were mixed to prepare a 20% by weight wettable powder. This wettable powder was dispersed in pure water to obtain a wettable powder dispersion liquid having a predetermined concentration.

On the other hand, prepare rice dishes, rice balls, radish seeds, and petri dishes in which firefly seeds were germinated, add the above wettable powder dispersions, and raise the seedlings for 7 days in a lighted constant temperature chamber at a temperature of 25 ° C to grow them. I observed. The growth inhibition effect on plants was evaluated according to the following criteria.

1: No effect 2: 25% growth suppression 3: 50% growth suppression 4: 75% growth suppression 5: Complete death From the above test results, it was found that the compound (I) of the present invention or a salt thereof has an excellent plant growth inhibitory effect on various plants.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References Chem. Pharm. Bull. Vol. 31, No. 6, pp. 1902-1909 (1983)

Claims (9)

[Claims] 1. A general formula (I) [In the formula, R ¹ is an alkyl group, a lower alkenyl group, a lower alkynyl group, a cycloalkyl group, a halogenated lower alkyl group, or a halogen atom, a lower alkyl group, a lower alkoxy group, a cyano group, a nitro group and a halogenated lower alkyl group. An aryl group which may be substituted with at least one group selected from the group consisting of groups, or a group consisting of a halogen atom, a lower alkyl group, a lower alkoxy group, a hydroxy group, a cyano group, a nitro group and a halogenated lower alkyl group. An aralkyl group which may be substituted with at least one group selected from R ² is a hydrogen atom, a halogen atom, an alkyl group, a lower alkenyl group, a lower alkynyl group, a cycloalkyl group, a halogenated lower alkyl group, or a halogen atom. , Lower alkyl group, lower alkoxy group, cyano group, nitro group and ha An aryl group which may be substituted with at least one group selected from the group consisting of rogenated lower alkyl groups, halogen atoms, lower alkyl groups, lower alkoxy groups, hydroxy groups, cyano groups, nitro groups and halogenated lower alkyl groups An aralkyl group which may be substituted with at least one group selected from the group consisting of groups; and R ³ is a hydrogen atom, a lower alkyl group, a lower alkenyl group, a lower alkynyl group, or a halogenated lower alkyl group, or R ² And R ³ together represent-(CH ₂ ) n- (n is 3 or 4); provided that R ² is a hydrogen atom and R ³ is a lower alkyl group,
R ¹ is other than an unsubstituted aryl group. ] A 1,3-oxazin-4-one derivative represented by: Wherein R ¹ is a halogen atom on the benzene ring of the general formula (I), C ₁ ~ ₄ alkyl group may be substituted with C ₁ ~ ₄ halogenated alkyl group, or C ₁ ~ ₄ alkoxy group, an alkyl 2. An aralkyl group having 1 to 4 carbon atoms in the moiety.
A compound as described. 3. R ² of the general formula (I) is a halogen atom, C ₁ to ₄
Alkyl group, C ₁ ~ ₄ halogenated alkyl group, or C ₁ ~ ₄
The compound according to claim 1, which is a phenyl group which may be substituted with an alkoxy group. 4. R ¹ of the general formula (I) is a ¹ -methyl-1-phenylethyl group which may have a halogen atom, an ethyl group, a trifluoromethyl group or a methoxy group in the benzene ring. The compound according to any one of 1 to 3. 5. The compound according to claim 1, wherein R ^{2 in the} general formula (I) is a phenyl group which may be substituted with a halogen atom, a methyl group, a trifluoromethyl group or a methoxy group. 6. The compound according to claim 1, wherein R ^{2 in the} general formula (I) is a bromine atom. 7. A compound represented by the general formula (II): R ¹ —N═CH ₂ (II) (wherein R ¹ has the same meaning as in the following formula (I)) and the general formula (III). ): (In the formula, R ² and R ³ have the same meanings as in the following formula (I).) A compound represented by the general formula (I) characterized by reacting: [In the formula, R ¹ is an alkyl group, a lower alkenyl group, a lower alkynyl group, a cycloalkyl group, a halogenated lower alkyl group, or a halogen atom, a lower alkyl group, a lower alkoxy group, a cyano group, a nitro group and a halogenated lower group. An aryl group which may be substituted with at least one group selected from the group consisting of alkyl groups, or a halogen atom, a lower alkyl group, a lower alkoxy group, a hydroxy group, a cyano group, a nitro group and a halogenated lower alkyl group. An aralkyl group which may be substituted with at least one group selected from the group; R ² is a hydrogen atom, a halogen atom, an alkyl group, a lower alkenyl group, a lower alkynyl group, a cycloalkyl group, a halogenated lower alkyl group, or halogen; Atoms, lower alkyl groups, lower alkoxy groups, cyano groups, nitro groups and ha An aryl group which may be substituted with at least one group selected from the group consisting of genated lower alkyl groups, halogen atoms, lower alkyl groups, lower alkoxy groups, hydroxy groups, cyano groups, nitro groups and halogenated lower alkyl groups An aralkyl group which may be substituted with at least one group selected from the group consisting of groups; and R ³ is a hydrogen atom, a lower alkyl group, a lower alkenyl group, a lower alkynyl group, or a halogenated lower alkyl group, or R ² And R ³ together represent-(CH ₂ ) n- (n is 3 or 4); provided that R ² is a hydrogen atom and R ³ is a lower alkyl group,
R ¹ is other than an unsubstituted aryl group. ] The manufacturing method of the 1, 3- oxazin-4-one derivative represented by these. 8. General formula (IV): (In the formula, R ¹ and R ³ have the same meanings as in the following formula (V).) A general formula characterized by reacting a compound represented by the following formula with bromine in the presence of an inorganic base in an inert solvent. (V): [In the formula, R ¹ is an alkyl group, a lower alkenyl group, a lower alkynyl group, a cycloalkyl group, a halogenated lower alkyl group, or a halogen atom, a lower alkyl group, a lower alkoxy group, a cyano group, a nitro group and a halogenated lower alkyl group. An aryl group which may be substituted with at least one group selected from the group consisting of groups, or a group consisting of a halogen atom, a lower alkyl group, a lower alkoxy group, a hydroxy group, a cyano group, a nitro group and a halogenated lower alkyl group. An aralkyl group optionally substituted with at least one group selected from R; R ³ represents a hydrogen atom, a lower alkyl group, a lower alkenyl group, a lower alkynyl group, or a halogenated lower alkyl group. ] The manufacturing method of the 5-bromo- 1,3- oxazin-4-one derivative represented by these. 9. General formula (I): [In the formula, R ¹ is an alkyl group, a lower alkenyl group, a lower alkynyl group, a cycloalkyl group, a halogenated lower alkyl group, or a halogen atom, a lower alkyl group, a lower alkoxy group, a cyano group, a nitro group and a halogenated lower alkyl group. An aryl group which may be substituted with at least one group selected from the group consisting of groups, or a group consisting of a halogen atom, a lower alkyl group, a lower alkoxy group, a hydroxy group, a cyano group, a nitro group and a halogenated lower alkyl group. An aralkyl group which may be substituted with at least one group selected from R ² is a hydrogen atom, a halogen atom, an alkyl group, a lower alkenyl group, a lower alkynyl group, a cycloalkyl group, a halogenated lower alkyl group, or a halogen atom. , Lower alkyl group, lower alkoxy group, cyano group, nitro group and ha An aryl group which may be substituted with at least one group selected from the group consisting of rogenated lower alkyl groups, halogen atoms, lower alkyl groups, lower alkoxy groups, hydroxy groups, cyano groups, nitro groups and halogenated lower alkyl groups An aralkyl group which may be substituted with at least one group selected from the group consisting of groups; and R ³ is a hydrogen atom, a lower alkyl group, a lower alkenyl group, a lower alkynyl group, or a halogenated lower alkyl group, or R ² and R ³ is, together with - indicating the (CH ₂₎ n- (n is 3 or 4). ] The plant growth inhibitor characterized by containing at least 1 sort (s) of the 1, 3- oxazin-4-one derivative represented by these as an active ingredient.